Cartoon of product release manner for BcelPL6, 1,4-β-d-mannuronic acid (green), and 1,4-α-l-guluronic acid (orange).
BcelPL6 binds to alginate and cleaves off a larger unsaturated oligosaccharide (up to DP7) (top). If the oligosaccharide is ≥DP4 and contains an M–M linkage, it can be cleaved again to yield DP2 (middle). This process continues until the final product mixture is achieved (bottom).